Cardiac pacing with implantable electronic cardiac devices and transvenous leads has been
introduced since 1960 and is considered a safe, effective and low-risk therapy. The most
common indications for permanent cardiac pacing are sinus node dysfunction and
atrioventricular blocks. In Europe, pacemaker implants exceed 1000 per million inhabitants.
The aim of this therapy is not only to improve patients survival but also their quality of
life, which is an essential aspect in assessing patients clinical status and prognosis.
Nowadays, five types of cardiac pacing are recognised in clinical practice:
Endocardial right chambers pacing: the device is implanted in the subcutaneous
subclavian area and it is connected to transvenous leads implanted in the right cardiac
chambers, which detect intrinsic electrical activity and stimulate when needed;
Epicardial pacing: this procedure is often performed in conjunction with cardiac
surgery;
Cardiac resynchronisation therapy (CRT): it delivers biventricular or left ventricular
pacing in order to correct interventricular electromechanical dyssynchrony and to
improve cardiac output;
Conduction system pacing: it stimulates the His bundle or the left bundle branch area
downstream of the conduction block, in order to restore a physiological
electromechanical activation.
Leadless pacing: via a percutaneous approach through a large-calibre vein, leadless
device is placed inside the right ventricle.
These pacing modalities have different possibilities to restore a normal cardiac
electromechanical activation, resulting in different degrees of mechanical efficiency in
terms of systolic output and diastolic pressures, with consequent effects on
improvement/onset of heart failure and cardiopulmonary performance of our patients.
Right ventricular pacing induces a dyssynchronous cardiac activation pattern that can lead to
left systolic dysfunction and a consequent increased risk of death related to the development
of heart failure.
These observations led to the study of alternative cardiac pacing modalities since the 1990s,
in order to improve the clinical outcome of patients with symptomatic bradyarrhythmias. The
study of pathological ventricular activation due to left bundle-branch block represents the
pathophysiological premise of cardiac resynchronisation in patients with systolic
dysfunctional heart failure, and constitutes the developmental model for physiological
pacing.
CRT improves mortality and quality of life in patients with heart failure and reduced left
ventricular ejection fraction. Typically left ventricular pacing is achieved by placing a
catheter in the posterolateral area through a venous branch of the coronary sinus.
Unfortunately, despite several years of experience in this field, clinical non-response to
this therapy is observed in between 20% and 40% of patients, mostly due to the inability to
reach the appropriate pacing site because of anatomical difficulties/absence of veins in the
target area.
Recently, conduction system pacing (CSP) has rapidly emerged as an alternative pacing
modality to both right ventricular pacing (RVP) and CRT, in order to achieve a more
physiological pacing. His bundle pacing (HBP) is considered the physiological pacing "par
excellence", but the results in literature show rather frequent technical difficulties due to
high pacing thresholds, inadequate ventricular signal amplitude for the detection of
intrinsic cardiac activity, low success rate and risk of progression of conduction system
pathology in patients with infranodal conduction defects.
Left bundle area pacing has more recently emerged as a viable alternative to achieve
physiological pacing with haemodynamic parameters similar to those of HBP, but with lower and
stable pacing thresholds, ventricular signal amplitude adequate for the detection of
intrinsic cardiac activity and high success rate.
Several experiences with different pacing systems have been published, mainly single-centre
studies with small sample sizes and different definitions of conduction system pacing
success.
In non-randomised comparative studies, and thus with methodological limitations, clinical
superiority over conventional right ventricular pacing, and a substantial efficacy equivalent
to CRT in patients with left bundle-branch block, has been shown, creating the preconditions
for widespread use of the CSP.
Considering, therefore, the widespread use of the latter technique and the high rate of
implants that can potentially benefit from physiological pacing, evaluating safety,
feasibility, timing and benefits becomes more crucial than ever.
Therefore, the goal of this observational study is to evaluate the clinical characteristics
of patients undergoing permanent cardiac pacing and to compare procedural efficacy and safety
of different implantation approaches in the clinical practice of the participating centres.
The contribution of non-fluoroscopic anatomical and electrophysiological reconstruction
systems to device implantation procedures will also be evaluated.
The investigators will collect clinical and procedural data from patients with an indication
for permanent cardiac pacing who have consecutively undergone an implantable electronic
device implant procedure at the Electrophysiology Laboratories of the participating centres
over a period of 120 months from the time of approval with a follow-up of an equal 120
months.
Patients will be classified according to the type of stimulation:
Right chambers endocardial pacing;
Cardiac resynchronisation therapy;
Conduction system pacing:
His bundle pacing
Left bundle branch area pacing. In addition, the efficacy and safety at 30 days,
and the efficacy and safety at 6 and 12 months of the various pacing modalities,
will be evaluated.
The investigators defined efficacy at 30 days the presence of stable electrical parameters -
or, if unstable, not requiring early re-intervention, the absence of cardiovascular
hospitalizations and the absence of cardiovascular death.
The investigators defined safety at 30 days the absence of procedural complications, such as
haematoma requiring re-intervention or with haemoglobin loss >2gr/dl, pneumothorax,
pericardial effusion requiring drainage, lead dislocation, cardiac implantable electronic
device (CIED) infection or a re-intervention for any cause.
Equally, the investigators defined efficacy at 6-12 months the presence of stable electrical
parameters - or, if unstable, not requiring re-intervention, the absence of cardiovascular
hospitalizations, the absence of cardiovascular death, the occurrence of heart failure, the
occurrence or worsening of atrial or ventricular tachyarrhythmias.
Therefore, the investigators defined safety at 6-12 months the proper functioning of the
device, the absence of infection and the absence of re-intervention for any cause.